The children of women who had vitamin D deficiency during pregnancy have a higher risk of developing multiple sclerosis (MS) later on in life, a new study out of Harvard University is reporting.

For this study, researchers, headed by Kassandra Munger of the Harvard T.H. Chan School of Public Health, recruited 193 people who were diagnosed with MS before 2009. All of the participants' mothers were involved in the Finnish Maternity Cohort, which had compared prenatal vitamin D levels. In that cohort, 176 mothers had children who were later diagnosed with the neurodegenerative condition and 326 mothers did not.

MS is an incurable condition that occurs when the immune system attacks the myelin sheath, which acts as the protective covering for nerve cells. The damage to the nerves ends up disrupting the brain's ability to communicate with the body, which can result in symptoms such as pain, vision loss and impaired coordination.

The researchers found that even though overall levels of vitamin D were not very sufficient in both groups, the levels in the control group were still better than the levels recorded in the group of women who gave birth to children who were later diagnosed with MS.

The team then compared blood samples and calculated that children with mothers whose vitamin D levels were insufficient during pregnancy had a 90 percent higher chance of being diagnosed with MS in comparison to children born to mothers who did not have as low vitamin D levels. The researchers argued that pregnant women and doctors have to pay closer attention to vitamin D levels.

"Correcting maternal vitamin D deficiency in early pregnancy may have a beneficial effect on risk of MS in the offspring," the authors concluded.

Previous studies have also found a link between vitamin D and MS. However, these studies, like this one, have only found associations and not a cause-and-effect relationship.

"The timing of vitamin D deficiency has been suggested as a critical co-variate to its effect on the risk of developing MS," Dr. Benjamin Greenberg added in a commentary published in JAMA Neurology. "The potential correlation between in utero vitamin D deficiency and MS would have both basic science and clinical implications."

The study was published in JAMA Neurology.